December 1703 finds Berry Grigsby living as Mary Lynn Nash in a small English village where she has fallen victim to Professor Fell's involuntary drug experiments. Her mind is quickly deteriorating under the drug’s influence, and the only way to save her is a potion book that was stolen in an attack on the village orchestrated by a mysterious madman going by the name Cardinal Black. Matthew Corbett has volunteered to travel with Julian Devane, a self-proclaimed "fool and bad man" in the employ of Professor Fell, to hunt down the potion book. 

The year is 1703. The place: The Carolina settlement of Charles Town. Matthew Corbett, professional 'problem solver,' has accepted a lucrative, if unusual, commission: Escorting a beautiful woman to a fancy dress ball. What should be a pleasant assignment takes a darker turn when Matthew becomes involved in a murder investigation.

The Providence Rider is the fourth installment in the extraordinary series of historical thrillers featuring Matthew Corbett, professional problem solver. The narrative begins in the winter of 1703, with Matthew still haunted by his lethal encounter with notorious mass murderer Tyranthus Slaughter. When an unexplained series of explosions rocks his Manhattan neighborhood, Matthew finds himself forced to confront a new and unexpected problem. Someone is trying - and trying very hard - to get his attention.

. Mister Slaughter opens in the emerging metropolis of New York City in 1702, and proceeds to take both Matthew and the reader on an unforgettable journey of horror, violence, and personal discovery. The journey begins when Matthew, now an apprentice problem solver for the London-based Herrald Agency, accepts an unusual and hazardous commission. Together with his colleague, Hudson Greathouse, he agrees to escort the notorious mass murderer Tyranthus Slaughter from an asylum outside Philadelphia to the docks of New York.

Robert McCammon brings the hero of his previous novel, Matthew Corbett, to 18th-century New York, where a killer wields a bloody and terrifying power over a bustling city carving out its identity - and over Matthew's own uncertain destiny.

The unsolved murder of a respected doctor has sent ripples of fear throughout a city teeming with life and noise and commerce. Who snuffed out the good man's life with the slash of a blade on a midnight street? The local printmaster has labeled the fiend "the Masker," adding fuel to a volatile mystery...